Fertility experts said the scratch was one of a number of dubious add-ons marketed to “vulnerable” would-be parents.

They called for health bosses to ban private clinics from offering the treatment to women referred for IVF by the NHS.

Meanwhile Professor Lord Robert Winston, who helped pioneer the technology, said: “Many experimental treatments during private IVF are extremely costly and are given without adequate scientific evidence of their efficacy.

“Patients should not have to pay these costs.”

Researchers at the University of Auckland performed the trial at 13 fertility centres across New Zealand, the UK, Belgium, Sweden and Australia.

The clinical pregnancy rate in the endometrial scratch group was 31.4 per cent, compared to 31.2 per cent in the control group, while live birth rates were 26.1 per cent in both groups.

Previous smaller trials had indicated there was an advantage to the treatment, particularly for women who had undergone multiple failed rounds of IVF, with doctors believing that the injury to the lining of the uterus causes an inflammatory response that helps embryos stick in the womb.

Addressing the European Society of Human Reproduction and Embryology annual meeting in Barcelona, Dr Sarah Lensen, who led the research, said: “Our results contradict those of many studies published previously.

“I think clinics should now reconsider offering endometrial scratch as an adjuvant treatment.”